Extrusion of Pre-gelatinised Flour from Plantains

AZSK twin-screw extruder from Coperion will soon go into service in Uganda for the production of pre-gelatinised matooke flour from non-storable plantains, also known as green or cooking bananas. The flour is simply stirred into hot or cold water to make matooke, which is a staple and easily digestible Ugandan meal. ZSK MEGAvolume PLUS twin-screw extruder was purchased by the Presidential Initiative for Banana Industrial Development (PIBID), which is part of a project aimed at promoting the sustainable production of plantains in Uganda, increasing local added value and at the same time improving the nutrition of the population.

The new production process, which has been specially tailored to the capabilities of local farmers, targets the production of flour, which will be transported and stored at the PIBID production centre at Bushenyi, where the new ZSK MEGAvolume PLUS twin-screw extruder, equipped with 54 mm diameter screws and a seven-barrel process section, is to be installed. A solids conveying and metering system feeds the plantain flour into the extruder, whilst a fine jet of water is injected into the second barrel of the process section. The cooking extrusion process now commences and the plantain flour is extruded at a typical temperature of between 140℃ and 150℃ into a modified, pre-gelatinised flour. Downstream of the extruder’s process section is a modified version of the Coperion ZGF 70 centric pelletizer, which is axially displaceable. This way the knife rotor can be attached to the die plate whilst the extruder is in operation. Due to the Vernier adjustment with scaling, an absolutely precise cut is possible. The pelletising system produces a directly expanded extrudate that can then be readily milled into soluble matooke flour after it has been dried.

The twin-screw extruder and the pelletising system fully meet the standards and requirements of the food industry. All parts of the extruder that come into contact with the product have been specially selected for food processing application. The outer surfaces of the process section are chemically nickel-plated. All oils and lubricants conform to FDA standards. The splash water protected design and the stainless steel cladding facilitate cleaning.

Dr. Florence Muranga, Director of PIBID, and further representatives of the initiative came to Stuttgart for the factory acceptance test. The completely assembled extrusion line was tested at Coperion’s food test lab using the original product. Also attending the tests in Stuttgart was Dr. Albert Esper of Innotech Ingenieursgesellschaft mbH, Altdorf. This engineering company specialises in processing technology applications in tropical and subtropical regions and was of invaluable assistance to the intercultural dialogue between PIBID and Coperion.

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